Description: Ubuntu 11.04 BETA I seems to not detect or acknowledge the presence of any wifi card, wifi is not listed on the wireless menu, and ifconfig/iwconfig do not list a wlan device. Commands such as   rfkill list  show the device, but as blocked.
WiFi light will not turn on with key command, either.

Problem: Once again, the Ubuntu team has provided incorrect default drivers for Broadcom devices. These directions will only help you to  gain some functionality from your wifi device. The wifi may not work to its full potential.

Solution: Navigate to Additional Drivers. To get here from Ubuntu 11.04, click on the power button on the desktop in the upper right hand corner, and click “System Settings”. Locate “Additional Drivers” under the Hardware category.

Remove/deactivate the Broadcom STA Wireless driver. Restart the computer.

Log in, and open a terminal. Then run:

sudo apt-get install firmware-b43-installer

Restart the computer again.

You should notice that your WiFi light has turned on.Wireless can not be enabled and disabled from the Network menu (next to the system clock).

A note: Usability of the card may be poor due to having “sketchy” drivers installed. The particular driver installed will work for most Broadcom cards, but may not offer the full features your card may typically have.

Please comment and share how well this worked for you (if at all) and any other solutions you may come across.